In the construction of flat roofed buildings, the roofs are commonly covered with a rubber membrane, and the membranes are in turn covered with a suitable ballast such as gravel or stones. Gravel stops are provided at the edge of the roof to retain the ballast on the roof and control water drainage, and also to function as a mechanical means for securing the edges of the rubber membrane to the edges of the roof.
Examples of gravel stops or gravel curbs for use in securing the edges of a rubber membrane to the edge of a roof are illustrated in Butzen, U.S. Pat. No. 4,419,850, issued Dec. 13, 1983; Patry, U.S. Pat. No. 4,037,372, issued July 26, 1977; Hickman, U.S. Pat. No. 4,472,913, issued Sept. 25, 1984; and Benoit, U.S. Pat. No. 4,437,283, issued Mar. 20, 1984. Attention is also directed to Josek, U.S. Pat. No. 3,365,847, issued Jan. 30, 1968; German Auslegeschrift No. 17 84 213; and Hickman, U.S. Pat. No. 4,071,987, issued Feb. 7, 1978. Attention is also directed to the publication of the Single Ply Roofing Institute titled "Wind Design Guide for Ballasted Single-Ply Roofing Systems".
It is necessary that the gravel stops secure the membrane in place with a grip sufficient to withstand a force of 90 lbs. per foot of length of the edge of the membrane. Additionally, the membrane securing structure should also be constructed in a manner which facilitates low cost installation of the structure used in mechanically securing the edge of the membrane down against the gravel stop.